This application claims the benefit of Korean Patent Application No. 1999-46344, filed on Oct. 25, 1999, under 35 U.S.C. xc2xa7119, the entirety of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to an array substrate for use in a liquid crystal display (LCD) device and a method of manufacturing the same.
2. Description of Related Art
A typical LCD device includes upper and lower substrates with a liquid crystal layer interposed therebetween. The upper substrate includes a color filter and a common electrode. The lower substrate includes a switching element and a pixel electrode and is called an array substrate.
FIG. 1 is a plan view illustrating an array substrate for use in a conventional LCD device. As shown in FIG. 1, the LCD device includes gate lines 13 arranged in a transverse direction and data lines 19 arranged in a longitudinal direction perpendicular to the gate lines 13. Gate pads 11 are formed at one terminal portion of the gate lines 13, and odd and even data pads 15a and 15b are formed at one terminal portion of the odd and even data lines 19a and 19b, respectively. Gate shorting bars 23 electrically connects the gate lines 13 with each other. Data shorting bars 29 electrically connect the data lines 19 with each other. Thin film transistors (TFTs) are arranged a crossing point of the gate and data lines 13 and 19. Pixel electrodes xe2x80x9cPxe2x80x9d are arranged on a region defined by the gate and data lines 13 and 19.
The gate line 13 includes odd and even gate lines, but one of the odd and even gate lines is not shown. The data lines 19 also include odd and even data lines 19a and 19b. The gate shorting bars includes odd and even gate shorting bars. The odd gate shorting bars connect the odd gate lines with each other, and the even gate shorting bars connect the even gate lines with each other, respectively, through the gate pads 11. The odd and even gate shorting bars are opposite to each other. The data shorting bars 29 also includes odd and even data shorting bars 29a and 29b. The odd data shorting bars 29a connect the odd data lines 19a with each other, and the even data shorting bars 29b connect the even data lines 19b with each other.
In FIG. 2 (which shows portion A of FIG. 1 in more detail), each of the TFTs includes a gate electrode 10, a source electrode 17, a drain electrode 18, and an active layer 16. The gate electrode 10 extends from the gate line 13, and the source electrode 17 extends from the data line 19. The source and drain electrodes 17 and 18 are spaced apart from each other and overlay opposite sides of the active layer 16, respectively. The drain electrode 18 is electrically connected with the pixel electrode xe2x80x9cPxe2x80x9d through a contact hole 5. The active layer 16 extends from an active line 28 under the data line 19.
The shorting bars 23 and 29 are provided for a short-circuit test between the two adjacent gate lines or the two adjacent data lines. In other words, in case of the data lines 19, as described above, since the odd shorting bars 29a connect the odd data lines 19a electrically and the even shorting bars 29b connect the even data lines 19b electrically, the odd and even shorting bars 19a and 19b are electrically separated from each other. Therefore, it can be tested whether the two adjacent data or gate lines are short or not.
In general, the even data shorting bar 29b is patterned along with the gate line 13, and later the odd data shorting bar 29a is formed at the same time as the data lines 19a and 19b, and then the even data shorting bar 29b is electrically connected with the odd data lines 19a while the pixel electrode P is formed. Therefore, the even data shorting bar 29b is made of the same metal as the data line, and the odd data shorting bar 29a is made of the same metal as the gate line.
The gate and data lines 13 and 19 are made of a conductive metal such as Cr, W and Mo, which are flexible materials. An insulating layer (not shown) that insulates each of the elements of the LCD device is made of SiO2 or SiNx. The active layer 16 and an active line 28 are made of semiconductor material such as amorphous silicon and polysilicon, which are very hard materials. Since the active line 28 that is relatively hard is formed under the data line 19, the data line 19 is not bent, whereupon a break or open circuit condition of the data line 19 is prevented. For example, when the array substrate is bent during its conveyance, the data line 19 may be cracked, leading to the open circuit.
To complete the array substrate described above, a depositing technique, a photolithography technique, and an etching technique are repeated several times.
Of these, the etching technique includes a dry-etching and a wet-etching. The dry-etching includes a plasma dry-etching, an ion beam milling etching, and a reactive ion etching. In wet-etching, acids and other chemical solutions are used as an etching. In chemical dry-etching, for example, the plasma dry-etching, plasma is used to generate gas radicals such as fluorine radicals in order to etch any portions of a thin film that are not covered by photoresist. In physical dry-etching, for example, ion beam milling etching, an ion beam is used in order to etch any portions of a thin film that are not covered by a photoresist.
Such a dry-etching technique requires a high electric field, so that static electricity may occur and be locally accumulated on the gate and data lines formed previously during the dry-etching process that is performed several times. The accumulated charges may cause a short-circuit between the data line and the gate electrode, for example, a portion C of FIG. 2.
In other words, note that the even data shorting bar 29b is formed together with the even data lines 19b. Since the gate shorting bars 23 also serve to discharge the static charges accumulated on the gate lines 13, a short-circuit between the data line and the gate line due to the accumulated charges may not occur. In the same way, the odd data lines 19a are connected to the odd data shorting bar 29a and so the charges are discharged, a short-circuit an odd data line 19a and a gate line 13 due to the accumulated charges may not occur. However, the even data shorting bar 29b is electrically connected with the even data lines 19b at a later time, when the pixel electrode is formed. Thus charges on the even data lines 19b are not discharged during a process of manufacturing the TFT, and so a short circuit between the odd data line 19b and the gate electrode can occur due to the accumulated static charges, leading to low manufacturing yields.
For the foregoing reasons, there is a need for an array substrate having a structure that prevents the effect of the static electricity generated during a process of manufacturing a thin film transistor.
To overcome the problems described above, embodiments of the present invention provide array substrates (and methods of making the same) for use in a liquid crystal display device, which has a structure that prevents the effect of the static electricity generated during the manufacturing process.
The present invention, in part, provides an array substrate for use in a liquid crystal display device, the array substrate including: gate lines arranged in a transverse direction and organized as odd and even gate lines; data lines arranged in a longitudinal direction perpendicular to the gate lines, and organized as odd and even data lines; gate pads arranged at a terminal portion of the gate lines, and organized as odd and even gate pads; data pads arranged at a terminal portion of the data lines, and being organized as odd and even data pads; gate shorting bars and organized as odd and even gate shorting bars, the odd gate shorting bar electrically connecting all of the odd gate lines through the odd gate pad, the even gate shorting bar electrically connecting all of the even gate lines through the even gate pad; data shorting bars organized odd and even data shorting bars, the odd data shorting bar electrically connecting all of the odd data lines through the odd data pad, the even data shorting bar electrically connecting all of the even data lines through the even data pad; and a first active line arranged between the data shorting bars and the data pads and electrically connecting all of the data lines.
The array substrate can further include a second active line arranged under the data line. The first and second active lines can be arranged on the same plane. The first and second active lines can be perpendicular to each other. The array substrate further can include a third active line formed under the odd shorting bars. The first, second and third active lines can be formed from the same stratum of one or more materials and are preferably electrically connected with each other. The first, second and third active lines can be made of a semiconductor material such as amorphous silicon and polysilicon.
The present invention, also in part, provides methods of manufacturing such array substrates for use in a liquid crystal display device. The methods include: providing a first intermediate structure having gate lines and an odd data shorting bar on a base substrate, the gate lines being organized as odd and even gate lines, the odd and even gate lines being organized as odd and even gate pads at a terminal portion thereof, respectively, and a first insulating layer on the exposed surface of the base substrate and the gate lines; forming an active stratum on the first insulating layer, the active stratum having a first active line adjacent to and parallel to the odd data shorting bar; forming data lines and an even data shorting bar on the active stratum and the first insulating layer to produce a second intermediate structure, the data line being organized as odd and even data lines and being connected with the first active line, the odd and even data lines having odd and even data pads at a terminal portion thereof, respectively, the even data shorting bar electrically connecting all of the even data lines; forming a second insulating layer on the second intermediate structure; and forming a connection layer to electronically connect the odd data shorting bar with all of the odd data lines.
The active stratum can further include a second active line formed under the data lines. The first and second active lines can be perpendicular to each other.
The active stratum can further include a third active line formed under the even data shorting bar. The first, second and third active lines are preferably electrically connected with each other.
The active stratum can be made of a semiconductor material such as amorphous silicon and polysilicon.
As described above, the array substrates for use in a liquid crystal display device according to the preferred embodiment of the present invention have a structure that discharges static charges on the gate and data lines generated during a process of manufacturing the TFT. As such, a short-circuit between the data line and the gate electrode can be prevented. And, for some embodiments, since the data pad connecting portion has no step portions, a line defect such as an open circuit is prevented. As a result, the array substrate has a high manufacturing yield.
Advantages of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.